The present invention relates to an adjustment device for a vehicle seat and more particularly, to a tilt adjustment device which allows the seat back of a vehicle seat to move relative to the base of the vehicle seat. This tilt device is also referred to as a recline mechanism and generally includes an inner gear and outer gear which moveable to relative one another in order to provide tilt adjustment of the seat back relative to the seat base. Typically, the inner gear is fitted within the outer gear and is at least one tooth smaller such than when a rotating adjustment element drives an eccentric ring or carrier about an axis causing wedge segments to be dragged and eccentrically wedged around the rotational axis, the outer gear moves radially about an axis. Typically, for each rotation of the carrier and wedge segments, the outer gear is driven approximately ten degrees about the axis. After the seat back is in the preferred adjusted position, the inner and outer gears are locked from relative movement due to the wedge segments ensuring that the inner and outer gears stay meshed.
The above described rotation mechanism is commonly referred to as a five-door rotary recline mechanism. The five-door recline mechanism works well for vehicles where in the rear seat has a separate door. For example, the five-door recline mechanism is common on the front seats of sedans, SUV's and minivans. However, for some seat locations such as the front seats of coupes, middles seats of station wagons, SUV's and minivans, as well as the rear seats of five-door or hatchback vehicles, it is desirable to at times allow the seat back to pivot freely forward. For example, it may be desirable to fold the seat back down to allow ingress and egress quickly without using the five-door rotary recline mechanism. Typically, recline mechanisms that include these additional features that allow free motion of the seat back relative to the seat base in certain conditions are referred to as three-door rotary recline mechanisms. The three-door recline mechanism generally includes a five-door mechanism described above, modified with minor changes, and an additional latch assembly that engages gear teeth on the outer edge of the outer gear. Generally, the latch assembly allows the seat back to be released from engaging the outer gear of the five-door recline mechanism such that it may rotate independent of the five-door recline mechanism that is included in the three-door recline mechanism. In some embodiments, the free rotation of the vehicle seat back also allows through additional elements for the track to be released and the seat to slide forward in one motion typically to allow easy ingress and egress from the vehicle seat.
Traditionally, the five-door recline mechanism was attached to a sidemember on the seat back which provided structural rigidity and was configured to be coupled to the frame of the seat back. The five-door recline mechanism was typically welded to this sidemember as generally illustrated in FIG. 3. However, if a recline mechanism requires the inclusion of an upper mount five-door mechanism otherwise known as a three-door recline mechanism, the sidemember 200 used on the seat back with a five-door recline mechanism was not useable with a three-door recline mechanism and required the use of a different sidemember 201, also illustrated in FIG. 3, that had an offset 202. Therefore, the prior sidemember 200 included a flat interface portion 204 if only a five-door recline mechanism was to be installed but if an upper mount five-door mechanism or a three-door recline mechanism was also to be installed, a different prior sidemember 201 that included the offset 202 and a raised mounting portion 206 to which the latch assembly of the three-door recline mechanism was mounted. Therefore, in the past each sidemember 200, 201 had a unique and specific surface profile for permitting the attachment of the relevant recline mechanism. This was required to obtain the desired mounting as well as a small package size as there was no way to mount a three-door recline mechanism to a sidemember 200 that was designed for use with a five-door recline mechanism.
As many of the seatbacks are formed in separate factories and are shipped for assembly elsewhere, increased inventory space is required as well as additional assembly time to create and assembly two different seat backs each including the different sidemembers 200 or 201 to the seat base. This additional inventory requirement and additional processing is not desirable.